Apparatus and Technique to Communicate With a Tubing-Conveyed Perforating Gun

ABSTRACT

A technique that is usable with a well includes providing a string that includes a tubing conveyed perforating (TCP) gun. The technique includes using a downhole component of the string to communicate uphole an indication of at least a depth or an orientation of the gun.

BACKGROUND

The invention generally relates to an apparatus and technique tocommunicate with a tubing conveyed perforating gun.

For purposes of producing well fluid from a formation, the formationtypically is perforated from within a wellbore to enhance fluidcommunication between the reservoir and the wellbore. To perform theperforating, a perforating gun typically is lowered downhole (on astring, for example) inside the wellbore to the region of the formationto be perforated. The perforating gun typically contains perforatingcharges (shaped charges, for example) that are arranged in a phasingpattern about the longitudinal axis of the gun and are radially orientedtoward the wellbore wall. The perforating charges are fired to piercethe well casing string (if the well is cased) and produce radiallyextending perforation tunnels into the formation.

Modern perforating technology has evolved from merely making simpleholes in the casing string to being customized, objective-orientedservices, which are integrated with sophisticated and versatilecompletion designs. Perforating is now used to optimize both permanentcompletions and temporary completions, such as drill stem testcompletions and workover completions. Along with services such ashydraulic fracturing, sand management, directional drilling ofextended-reach and horizontal wells, completion fluid engineering andwell testing, engineered perforating to achieve communication betweenthe formation and the wellbore has become an important factor inenhancing the well's productivity.

There are many factors to a successful perforating operation, such asthe ability to precisely control the depth of the perforating gun or theangular orientation of the perforating gun about the gun's longitudinalaxis. Another factor associated with the success of a perforatingoperation is the time required to perform the operation.

The manner in which a perforating operation is conducted also depends onthe type of perforating gun. For example, the positioning of aconventional tubing conveyed perforating (TCP) gun typically iscontrolled solely on logs and other data that are obtained prior to theperforating operation. Furthermore, parts of the operations' success andperformance typically are assessed after the job, i.e., after the gunstring is pulled out of hole and other services are performed (aproduction logging tool to measure downhole flow rates, for example).

SUMMARY

As an example, a technique that is usable with a well includes providinga string that includes a tubing conveyed perforating (TCP) gun. Thetechnique includes using a downhole component of the string tocommunicate uphole an indication of at least a depth or an orientationof the gun.

As another example, a system usable with a well includes a string thatis to be disposed in the well. A TCP gun and a transmitter are disposedin the string. The transmitter communicates uphole an indication of atleast a depth or an orientation of the TCP gun.

Advantages and other features of the invention will become apparent fromthe following drawing, description and claims.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 and 3 are schematic diagrams of tubing conveyed perforating(TCP) gun systems according to different examples.

FIG. 2 is a flow diagram depicting a technique to position and fire aTCP gun according to different examples.

FIG. 4 is a flow diagram depicting a technique to position and firemultiple TCP guns according to an example.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments are possible.

As used here, the terms “above” and “below”; “up” and “down”; “upper”and “lower”; “upwardly” and “downwardly”; and other like termsindicating relative positions above or below a given point or elementare used in this description to more clearly describe some embodimentsof the invention. However, when applied to equipment and methods for usein wells that are deviated or horizontal, such terms may refer to a leftto right, right to left, or diagonal relationship as appropriate.

FIG. 1 depicts an example of a tubing conveyed perforating (TCP) system5 according to an example. In general, the TCP system 5 includes atubing string 14 that extends downhole into a wellbore 11. The tubingstring 14 may be one of many different types of tubing strings, such asa production tubing string, a test string, a drill stem test (DST)string, etc. Regardless of its particular application, the tubing string14 includes at least one TCP perforating gun, such as a TCP gun 30 thatis depicted in FIG. 1.

In the context of this application, a “TCP gun” means a perforating gunthat is constructed to be fired in response to a pressure-based stimulusor pressure-based stimuli that are communicated downhole through acentral passageway of a tubing string from the surface of the well to aposition near (within 10 feet, for example) or at the TCP gun. Thepressure stimulus or stimuli may be in the form of command-encodedpressure pulses, absolute pressures, differential pressures, etc. As anon-limiting example, the perforating charges of the TCP gun 30 may befired by increasing the internal pressure of the tubing string 14 abovea threshold, such that the TCP gun 30 responds to the increased pressurelevel by firing its perforating charges.

It is noted that, as described below, the string 14 includes a downholetelemetry system 20 for purposes of establishing uphole communication,and the uphole communication may involve, for example, the use ofpressure-based stimuli that are communicated uphole through the string,for example, as well as the use of other types of stimuli (acousticstimuli, electromagnetic stimuli, electrical stimuli, etc.) that may ormay not be communicated through the string 14.

Although FIG. 1 depicts the tubing string 14 as extending downholeinside a borehole 11 that is cased by a casing string 13, it is notedthat FIG. 1 is merely an example of one out of many possibleimplementations of a TCP system. In this manner, the wellbore in whichthe TCP gun 30 extends may be cased or uncased, depending on theparticular implementation. Furthermore, the TCP gun 30 may extend in adeviated or highly deviated lateral wellbore, in accordance with otherimplementations. Additionally, the TCP perforating system 5 may be usedin a terrestrial-based subterranean well or in a subsea well, dependingon the particular implementation.

Before the perforating charges of the TCP gun 30 are fired, the TCP gun30 is first run downhole as part of the string and using real timeposition feedback that is provided by the downhole telemetry system 20(as described below), the TCP gun 30 is appropriately positioned. Thus,in contrast to conventional TCP systems, the TCP gun 30 is not blindlypositioned; but rather, real time downhole position feedback isprovided, which permits an operator at the surface of the well tomonitor the feedback and make the necessary adjustments to preciselyposition the gun 30. In general, the TCP gun's “position” refers to theangular orientation of the TCP gun 30 (i.e., the azimuth, or angle, ofthe TCP gun 30 about the gun's longitudinal axis 19 and referred toherein as the gun's “orientation”) and the depth of the gun 30.

The downhole telemetry system 20 is positioned downhole near (within tenfeet, for example) the TCP gun 30 and is constructed to communicate witha telemetry system 12 that is disposed at the surface of the well. Thecommunication between the telemetry systems 12 and 20 may occur throughthe tubing string 14 (acoustic or fluid pulse-type communication), forexample; through wired communication lines; through electromagnetic (EM)communication telemetry through signals 16 and 17 as depicted in FIG. 1;or through another type of wireless or wired telemetry communicationscheme or medium, depending on the particular implementation.

In general, a transmitter 27 of the downhole telemetry system 20 isconstructed to generate stimuli (pressure stimuli, acoustic stimuli,electrical stimuli, electromagnetic (EM) stimuli, etc) that are receivedby the surface telemetry system 12 for purposes of communicating anindication of the position (orientation and/or depth) of the TCP gun 30to the surface of the well in real time. For example, the transmitter 27may communicate indications of the orientation and depth of the TCP gun30 to the surface telemetry system 12. Therefore, an operator at thesurface of the well may, based on the received position of the TCP gun30, take appropriate measures to ensure that the TCP gun 30 is at theappropriate position before undertaking measures to fire perforatingcharges of the gun 30.

The downhole telemetry system 20 may also include a receiver 28. Ingeneral, the receiver 28 may communicate with the surface telemetrysystem 12 for purposes of receiving command-encoded stimuli that directpositioning of the TCP 30, in accordance with some implementations. Inother implementations, commands are not communicated downhole forpurposes of changing the position of the TCP gun 30; but rather, thestring 14 is physically manipulated to change the gun's position, asfurther described below. It is noted that the receiver 28 may also servethe dual function of receiving a pressure stimulus that encodes acommand to fire the gun's perforating charges, although a separatereceiver (not shown in FIG. 1) may be part of the TCP gun for thispurpose, in other implementations.

In addition to the downhole telemetry system 20, the tubing string 14may include other devices related to providing feedback of the TCP gun'sposition and positioning the gun 30. For example, the tubing string 14may include a downhole stored energy source, such as a battery 22, forpurposes of supplying power to the electrical components of the string14, such as the downhole telemetry system 20. The battery 22 may supplypower to other components of the tubing string 14, such as a depthmeasuring device 24, an orientation sensing device 33, a gun orientingdevice 31 (if an active power consuming device) and other powerconsuming components of the TCP gun 30, as non-limiting examples.

The depth measuring device 24 may take on numerous forms, such as acasing collar locator (CCL), a gamma ray device, etc., depending on theparticular implementation. In this regard, the signal that is providedby the CCL or gamma ray device in real time to the surface of the well(via the downhole telemetry system 20) may be correlated at the surfacewith a prior well log to determine the depth of the TCP gun 30.Regardless of its particular form, the depth measuring device 24 istherefore constructed to provide an indication of the depth of theperforating gun 30 and interact with the transmitter 27 for purposes ofcommunicating an indication of the depth of the TCP gun 30 to thesurface of the well in real time.

The orientation-sensing device 33 senses the angular orientation of theTCP gun 30. As a non-limiting example, the orientation-sensing device 33may be a gyroscope in one implementation. The signal that is provided bythe orientation-sensing device 33 is provided to the transmitter 27,which relays the signal to the surface of the well in real time.

In some implementations, the gun orienting device 31 is an activeorienting device that orients the TCP gun based on a command that iscommunicated downhole and received by the receiver 28. Morespecifically, in some implementations, the gun orienting device respondsto command-encoded stimuli that are transmitted from the surface toincrementally or absolutely orient the TCP gun 30. As a non-limitingexample, the orienting device 31 may include an electric motor (as anon-limiting example), which receives electric power from the battery 22and a command interface (not shown) to receive signals that are receivedby the downhole telemetry system 20. The command interface decodes anycommands for the device 31 and generates the appropriate control signalsfor the motor to rotate the TCP gun 30 by the desired position.

As a non-limiting example, in one implementation, the surface telemetrysystem 12 and the downhole telemetry system 20 may communicatewirelessly using extremely low frequency electromagnetic (EM) signals.In this regard, the bidirectional signals 16 and 17, which arecommunicated between the telemetry systems 12 and 20, may employelectromagnetic carrier waves that have frequencies in the range of 0.1to 1.0 Hertz (Hz). As a more specific example, the frequency range maybe in the range of 0.25 to 8 Hz, as a non-limiting example. As anothernon-limiting example, the distance between the telemetry systems 12 and20 may be between approximately 3000 meters (m), in someimplementations, although larger or smaller distances may exist in otherapplications.

In some implementations, the EM communication between the telemetrysystems 12 and 20 is accomplished by the injection of a modulatedcurrent into the formation via an electrical dipole. The voltagedifference induced by the circulating current is measured along thewalls of the casing string 12 by a repeater or between the well head anda remote stake at the surface. The voltage is demodulated to extract theinformation from the signal. The communication itself may be based onphase modulation of the injected current, although other types ofmodulation (frequency modulation, for example) may be used in otherimplementations. As a non-limiting example, the bit rate may beapproximately one bit per second, and data frames in the messages may beapproximately one minute in length, although other data rates and framerates are contemplated in other implementations.

Referring to FIG. 2 in conjunction with FIG. 1, in accordance with someimplementations, a technique 100 may be used for purposes of positioningand firing the TCP gun 30. Pursuant to the technique 100, a stringcontaining a TCP gun is run into a well, pursuant to block 104. Aprocedure then begins to properly position the TCP gun at theappropriate orientation and depth. In this positioning, an indication ofat least a depth or orientation of the gun is communicated in real timefrom a location downhole near the gun to a location near the surface ofthe well, pursuant to block 108.

Based on the indication(s), a decision is then made (diamond 112)whether the TCP gun is ready to fire. If not, then at least oneiteration is performed in adjusting the position of the TCP gun. Forexample, an indication of at least one command to regulate theorientation of the TCP gun may be wirelessly communicated from thesurface to a position near the gun, pursuant to block 114. These actionsmay also or alternatively include selectively physically manipulatingthe string that contains the TCP gun to adjust the depth of the gun,pursuant to block 116. The iteration proceeds by returning to block 108in which an indication of at least the depth or azimuth of the gun iscommunicated uphole, pursuant to block 108. The TCP gun is ultimatelyfired (block 120) when the iteration ends upon the determination thatthe TCP gun is ready to fire, pursuant to diamond 112.

Other implementations are contemplated and are within the scope of theappended claims. For example, in another implementation, the TCP gun 30may be oriented by using a passive orientation system, such as swivelsand weights, instead of the active orientation system that is describedabove. For this passive orientation system, the string 14 may be lifted,run further downhole and/or rotated to adjust the orientation of the TCPgun 30 based on the indication of the gun's orientation that is providedin real time by the downhole telemetry system 20. In this manner,adjusting the depth of the string 14 also adjusts the rotation of theTCP gun 30 due to the changing inclination of the wellbore 11.

As another example of a variation, although FIG. 1 depicts a TCP system5 for a single TCP gun, the systems and techniques that are disclosedherein may likewise be applied to a tubing string 202 that containsmultiple TCP guns 30, as depicted in FIG. 3. In this regard, referringto FIG. 3, the tubing string 202 of a multiple TCP gun perforatingsystem 200 includes two or more perforating units 220 (perforating units220 ₁ to 220 _(N), being depicted as examples in FIG. 3), which arespaced apart at desired intervals in the well. For this example, eachperforating unit 200 includes a TCP gun 30, a depth measuring device 24,an orientation-sensing device 33 and an orienting device 31.

For each unit 220, the depth measuring device 24 senses the depth of theassociated TCP gun 30 and communicates this depth to the transmitter 27,which, in turn, wirelessly communicates an indication of this depth tothe surface in real time.

Likewise, the orientation-sensing device 33 for each unit 220communicates an indication of the measured orientation of the associatedTCP gun 30 and communicates this measured orientation to the transmitter27 which, in turn, communicates an indication of the orientation to thesurface in real time. Additionally, the orienting device 31 of each unit220 passively or actively orients its associated TCP gun 30, asdescribed above.

It is noted that FIG. 3 merely depicts an example of a multiple TCP gunstring. Other variations are contemplated and are within the scope ofthe appended claims. For example, in other arrangements, eachperforating gun unit 220 may include a telemetry system, similar indesign to the telemetry system 20. As another example, orienting ordepth sensing devices may be shared by one or more TCP guns 30. Asanother example, a single motor or single weight and swivel system maybe used to orient multiple TCP guns 30.

Multiple TCP guns of a particular tubing string may be positioned andfired, according to a technique 300 that is depicted in FIG. 4.Referring to FIG. 4, the technique 300 includes running a string thatcontains multiple TCP guns into a well, pursuant to block 304. For eachof the TCP guns, an indication of at least the depth or orientation ofthe gun is communicated to the surface of the well in real time,pursuant to block 308. Based on these indications, a determination isthen made, pursuant to diamond 312, whether the TCP guns are ready tofire. If so, then the TCP guns are fired, pursuant to block 320.Otherwise, for each gun that is not appropriately positioned, anindication of at least one command may be wirelessly communicateddownhole to regulate the orientation of the gun, pursuant to block 314.Furthermore, the string may be physically manipulated to adjust thedepth of the guns, pursuant to block 316. Alternatively, the string maybe physically manipulated to control a passive orientation system. Whena decision is ultimately made that the guns are appropriatelypositioned, pursuant to diamond 312, then the perforating guns arefired, pursuant to block 320.

It is noted that FIG. 4 is merely an example, as other variations arecontemplated and are within the scope of the appended claims. Forexample, as another variation, all of the guns may not be finallypositioned before being fired. In this regard, in this implementation,one or more TCP guns may be positioned and then fired, another set ofone or more TCP guns may then be positioned and fired, etc.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art, having the benefit ofthis disclosure, will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover all suchmodifications and variations as fall within the true spirit and scope ofthis present invention.

1. A method usable with a well, comprising: providing a stringcomprising a tubing conveyed perforating gun in the well; and using adownhole component of the string to communicate uphole an indication ofat least a depth or an orientation of the gun.
 2. The method of claim 1,wherein the act of using comprises communicating the indication in realtime.
 3. The method of claim 1, wherein the act of using compriseswirelessly communicating the indication.
 4. The method of claim 1,wherein the act of using comprises communicating an electromagneticsignal having a frequency in the range of 0.1 to 1.0 hertz.
 5. Themethod of claim 1, further comprising: measuring at least the depth ofthe perforating gun or the orientation of the perforating gun.
 6. Themethod of claim 1, further comprising: communicating downhole from thesurface of the well an indication of a command to control theorientation of the perforating gun.
 7. The method of claim 1, furthercomprising: physically manipulating the string to adjust the depth ofthe perforating gun in response to the communication.
 8. The method ofclaim 1, further comprising: physically manipulating the string toadjust the orientation of the gun in response to the communication. 9.The method of claim 1, further comprising: firing the perforating gunafter the communication.
 10. A system usable with a well, comprising: astring to be disposed in the well; a tubing conveyed perforating gun tobe disposed in the string; and a transmitter to be disposed in thestring to communicate uphole an indication of at least a depth or anorientation of the gun.
 11. The system of claim 10, wherein thetransmitter is part of a wireless telemetry system to wirelesslycommunicate the indication.
 12. The system of claim 10, wherein thetransmitter is adapted to communicated the indication in real time. 13.The system of claim 10, further comprising: an orientation device to bedisposed in the string near the perforating gun to orient the gun inresponse to a remote communication from the surface of the well.
 14. Thesystem of claim 10, further comprising: a battery to provide power tothe transmitter.
 15. The system of claim 10, wherein the transmitter isadapted to communicate the indication using an electromagnetic carrierwave having an associated carrier frequency in the range of 0.1 to 1.0hertz.
 16. The system of claim 10, further comprising: a depth measuringdevice to be disposed in the string to measure the depth of theperforating gun.
 17. The system of claim 10, further comprising: anorientation sensing device to be disposed in the string to measure theorientation of the perforating gun.
 18. The system of claim 17, whereinthe orientation device comprises a motor to selectively rotate theperforating gun in response to a command received at a position near theperforating gun and communicated from a position near the surface. 19.The system of claim 10, further comprising: a receiver to be disposed inthe string to receive an indication of a indication of a command tocontrol an orientation of the perforating gun, the indication beingcommunicated from a position near the surface of the well to a positionnear the perforating gun.
 20. The system of claim 10, furthercomprising: at least one additional tubing conveyed perforating gun tobe disposed in the string, wherein the transmitter is part of atransmission system to be disposed in the string to communicate from afirst position near the perforating gun to a second position near thesurface of the well, an indication of at least a depth or an orientationof each of said at least one additional gun.